Are you asking where it is? If so, its attached to the fuel pump assembly inside the fuel tank. (under the rear seat)
If you didn't put the Walbro in, then you need to know that when you crack that access panel open, most likely you will need to replace that o-ring that seals it. Otherwise, you will get a constant gas smell, most likely.
Might I suggest that a more probable part to trplace is the fuel filter in the engine bay, It's like $5 - $10 at a parts store, and super easy to replace. (10 minutes MAX)